WASHINGTON (CNN) --U.S. intelligence agencies, including the FBI and CIA, "missed opportunities" to disrupt terrorism prior to the September 11, 2001, attacks, according to a critical congressional report released Thursday.

And, according to the report, senior military officials were poised to attack terrorist mastermind Osama bin Laden prior to September 11, but lacked the intelligence they needed to execute their plans. The report also questions Saudi Arabia's cooperation in earlier terror probes and examines its link to the hijackers.

The roughly 800-page report does not point to any single clue that could have definitely thwarted the September 11 plot, but says "various threads and pieces of information" were either overlooked or not put together.

"No one will ever know what might have happened had more connections been drawn between these disparate pieces of information. ... The important point is that the intelligence community, for a variety of reasons, did not bring together and fully appreciate a range of information that could have greatly enhanced its chances of uncovering and preventing bin Laden's plan to attack the United States on September 11, 2001," says the report.

As an example, the report cites contacts some of the hijackers had with individuals in the United States -- some of whom were already on the FBI's radar screen.

At least 14 people who had contact with six of the hijackers before the attacks had come to the FBI's attention during counterterrorism or counterintelligence inquiries.

The report says four of the 14 people were the focus of active FBI investigations while the hijackers were in the United States. The contacts helped them find housing, open bank accounts, obtain driver's licenses and locate flight schools, the report says. But a government official told CNN the FBI doesn't believe any of those individuals knew of the hijacking plot.

San Diego connection

The report singles out as the intelligence community's "best chance" to unravel the plot connections that two of the hijackers, Nawaf Alhazmi and Khalid Almihdhar, made as they settled in the San Diego area in January 2000. Both men were among the hijackers who flew American Airlines Flight 77 into the Pentagon.

CNN previously reported Alhazmi and Almihdhar, while in San Diego, lived in a house belonging to a man who was an FBI informant but who, sources have said, had no information about the men's intentions.

But one FBI agent who was responsible for the informant in San Diego told the joint inquiry that he was unaware that intelligence information was available on the two hijackers before September 11.

"It would have made a huge difference," the agent said. "We would have immediately opened ... investigations."

The intelligence community, for a variety of reasons, did not bring together and fully appreciate a range of information that could have greatly enhanced its chances of uncovering and preventing Osama bin Laden's plan to attack the United States on September 11, 2001.

-- Congressional report

The report pointedly notes that 15 of the 19 hijackers "were Saudi nationals who received visas in Saudi Arabia," and says that some U.S. government personnel described Saudi officials as "uncooperative" in terror probes prior to September 11, 2001.

The Saudi references -- many details of which were redacted from the report -- drew an angry response from Prince Bandar bin Sultan, the Saudi ambassador to the United States, who said the report was being used to "malign our country and our people."

Redacted information

One organization representing families who lost loved ones in the attacks called on the Bush administration to release the redacted information, particularly details on Saudi Arabia.

"We seek to uncover facts some powerful people may want hidden, but we are serious about stopping the flow of money from Saudi Arabia to al Qaeda," said the statement from 9/11 Families United to Bankrupt Terrorism.

The report is the result of a 10-month joint investigation by House and Senate intelligence committees looking into intelligence and security lapses leading to the mass killings when 19 terrorists commandeered four commercial jets and crashed two of them into the World Trade Center in New York and one into the Pentagon outside Washington. The fourth crashed in a field in Pennsylvania. The attacks killed nearly 3,000 people.

Much of the information in the report was previously made public. But the report -- the product of 5,000 interviews and a review of nearly 1 million documents -- contains new details and examples.

"The attacks of September 11th could have been prevented if the right combination of skill, cooperation, creativity and some good luck had been brought to the task," said Sen. Bob Graham, a former chairman of the Senate Intelligence Committee, and one of the leaders of the joint investigation.

Graham, a Democratic presidential hopeful, faulted the White House for what he described as its reluctance to declassify some material, a sentiment that was echoed by House Minority Leader Nancy Pelosi, D-California, who also served on the joint panel.

Republican lawmakers, who joined Graham at a news conference releasing the report, did not criticize the White House, but said the report highlighted intelligence failures and underscored the need for further reform.

The report included some 19 recommendations to bolster counterterrorism efforts; those recommendations were originally released last year.

"I think the basic tenet that we learned is a lack of coordination and sharing of information, different cultures in the community of intelligence," said Sen. Richard Shelby, R-Alabama, a former chairman of the Senate Intelligence Committee. "We have done our job, and now we have got to do more legislatively and the people who run the intelligence community have got to do theirs."

In the wake of the September 11 attacks, Congress approved the creation of a Department of Homeland Security to increase cooperation between the CIA and FBI and serve as an umbrella for other agencies that deal with homeland security.

In a written statement, FBI Director Robert Mueller thanked the joint committee for the report, saying it would generate a "constructive discussion." He also said the agency has already implemented or is in the process of implementing many of the recommendations on improving counterterroism.